16 young men in long-term remission after standard treatment for the early stages of Hodgkin's disease were examined for testicular function 48 to 125 months after termination of therapy. The patients had received mantle field irradiation, plus either irradiation of infradiaphragmatic lymph nodes (7 patients) or 6 cycles of MOPP (9 patients). 5 patients had almost normal semen quality judged by seminal fluid analysis. 11 patients had reduced semen quality (8 severely reduced) and often elevated FSH values. Semen samples of poor quality were significantly more common in patients treated with MOPP (7/9) than in those treated with infradiaphragmatic irradiation (1/7). One patient showed signs of regeneration of spermatogenesis. None had experienced reduction in libido and sexual performance after therapy; correspondingly, none had below normal testosterone values or elevated LH values. Patients should be informed about the risk of infertility before treatment. If in a given case several treatment options with equal prospective antineoplastic effect are weighed against one another, the patient's possible desire to retain fertility should favour the use of radiotherapy as opposed to chemotherapy, especially including alkylating agents.